1. Field of Invention
The invention generally relates to multi media and more particularly to transform based compression system for generating multiple descriptions of data.
2. Description of the Related Art
Typically, digital information is compressed using a preselected format or process by an encoder. However, conventional digital consumer formats such as High Definition Television (HDTV), Digital Versatile Disc or Video Disc (DVD), Advanced Television Systems Committee (ATSC), Digital Video Broadcast (DVB), Digital Satellite System (DSS) operate at various specific resolutions, frame rates and/or bit rates. Accordingly, in order to cater to the various formats, a compression technique that can generate multiple descriptions of video is required.
Current video compression standards that provide multiple descriptions do so in an innate form or are targeted toward a discrete application. For example, Joint Photographic Experts Group (JPEG) 2000 can generate multiple descriptions of video by reducing the video. However, being intraframe and wavelet based, JPEG 2000 inherently provides lower resolution images. Moreover, it is restricted to being dyadic, i.e. reduction factors are multiples of two. Motion Picture Experts Group (MPEG) 4 also supports multiple description discrete cosine transform (DCT) that targets limited or fixed bandwidth applications such as Internet video. In this technique, a rudimentary form of the video is transmitted. Consecutive transmissions are made to enhance the details (bits) in the video. A major disadvantage in this approach is motion compensation.
Therefore there is a need for a more versatile, simple and/or efficient system that can generate multiple descriptions of video or video sequences.
Embodiments disclosed herein address the above stated needs by providing a system for generating multiple descriptions of video. In one embodiment, a method for generating multiple descriptions of compressed data comprises generating a quantized bit stream using a reference quantization step; and re-quantizing the quantized bit stream using a first quantization step to generate a first description of compressed data, wherein the first quantization step is determined based on a first required scaling of the reference quantization step. An apparatus for generating multiple descriptions of compressed data comprises means for generating a quantized bit stream using a reference quantization step; and means for re-quantizing the quantized bit stream using a first quantization step to generate a first description of compressed data, wherein the first quantization step is determined based on a first required scaling of the reference quantization step. In the above embodiments, the quantized bit streams may be re-quantized using a second quantization step to generate a second description of compressed data, wherein the second quantization step is determined based on a second required scaling of the reference quantization step.
In another embodiment, an apparatus for generating multiple descriptions of compressed data comprises a transform module configured to generate transform coefficients from input data; and a quantization module coupled to the transform module, the quantization module configured to quantize the transform coefficients using a reference quantization step and to re-quantize the quantized transform coefficients using different quantization steps to generate multiple descriptions of compressed data, wherein each of the different quantization step is determined based on a required scaling of the reference quantization step. The quantization module may comprise a first quantization module configured to quantize the transform coefficients using the reference quantization step; and a second quantization module configured to re-quantize the quantized transform coefficients using the different quantization steps.
In further embodiment, a method for generating compressed data comprises accessing a quantized bit stream generated using a reference quantization step; and re-quantizing the quantized bit stream using a first quantization step to generate a first description of compressed data, wherein the first quantization step is determined based on a first required scaling of the reference quantization step. An apparatus for generating compressed data comprises means for accessing a quantized bit stream generated using a reference quantization step; and means for re-quantizing the quantized bit stream using a first quantization step to generate a first description of compressed data, wherein the first quantization step is determined based on a first required scaling of the reference quantization step. In the embodiments, the quantized bit stream may be re-quantize using a second quantization step to generate a second description of compressed data, wherein the second quantization step is determined based on a second required scaling of the reference quantization step.
In still another embodiment, an apparatus for generating compressed data comprises a storage medium configured to store a quantized bit stream generated using a reference quantization step; and a quantization module coupled to the storage medium and configured to re-quantize the quantized bit stream using different quantization steps to generate multiple descriptions of compressed data, wherein each of the different quantization step is determined based on a required scaling of the reference quantization step. The storage medium may be configured to store an archival compressed bit stream as the compressed bit stream.
In yet another embodiment, a method for generating multiple descriptions of compressed data comprises generating a quantized bit stream using a reference quantization step; encoding the quantized bit stream; decoding the encoded quantized bit stream; and re-quantizing the decoded quantized bit stream using a first quantization step to generate a first description of compressed data, wherein the first quantization step is determined based on a first required scaling of the reference quantization step. An apparatus for generating multiple descriptions of compressed data comprises means for generating a quantized bit stream using a reference quantization step; means for encoding the quantized bit stream; means for decoding the encoded quantized bit stream; and means for re-quantizing the decoded quantized bit stream using a first quantization step to generate a first description of compressed data, wherein the first quantization step is determined based on a first required scaling of the reference quantization step. In the embodiments, the decoded quantized bit stream may be re-quantized using a second quantization step to generate a second description of compressed data, wherein the second quantization step is determined based on a second required scaling of the reference quantization step.
In still a further embodiment, an apparatus for generating multiple descriptions of compressed data comprises a quantization module configured to generate a quantized bit stream using a reference quantization step; a coding module coupled to the quantization module and configured to encode the quantized bit stream; and a decoding module configured to decode the encoded quantized bit stream; wherein the quantization module is configured to re-quantize the decoded quantized bit stream using different quantization steps to generate multiple descriptions of compressed data, wherein each of the quantization step is determined based on a required scaling of the reference quantization step. The quantization module may comprise a first quantization module configured to generate the quantized bit stream using the reference quantization step; and a second quantization module configured to re-quantize the decoded quantized bit stream using the different quantization steps to generate the multiple descriptions of compressed data.
In yet a further embodiment, a method for generating compressed data based on encoded quantized bit steam comprises accessing compressed bit stream generated by quantization using a reference quantization step; decoding compressed bit stream to generate decoded quantized bit stream; and re-quantizing the decoded quantized bit stream using a first quantization step to generate a first description of compressed data, wherein the first quantization step is determined based on a first required scaling of the reference quantization step. An apparatus for generating compressed data based on encoded quantized bit steam comprises means for accessing compressed bit stream generated by quantization using a reference quantization step; means for decoding compressed bit stream to generate decoded quantized bit stream; and means for re-quantizing the decoded quantized bit stream using a first quantization step to generate a first description of compressed data, wherein the first quantization step is determined based on a first required scaling of the reference quantization step. In the embodiments, the decoded quantized bit stream may be re-quantized using a second quantization step to generate a second description of compressed data, wherein the second quantization step is determined based on a second required scaling of the reference quantization step.
In still yet another embodiment, an apparatus for generating multiple descriptions of compressed data based on encoded quantized bit steam comprises a storage medium configured to store a compressed bit stream generated by quantization using a reference quantization step; a decoding module configured to decode the compressed bit stream; and a quantization module configured to re-quantize the decoded compressed bit stream using different quantization steps to generate multiple descriptions of compressed data, wherein each of the quantization step is determined based on a required scaling of the reference quantization step. The storage medium may be configured to store an archival compressed bit stream as the compressed bit stream.